This paper provides an architectural study of optical ring trunk-transmission networks using either Time Division Multiplexing (TDM) or Wavelength Division Multiplexing (WDM). A timeslot arrangement algorithm for distributed controlled TDM rings is proposed that minimizes the number of slots (wavelengths) required in bi-directional ring networks. This algorithm is applied in a straightforward manner to wavelength arrangement in WDM ring networks. The technique, characterized by timeslot (or wavelength) conversion, realizes common add/drop procedures in all Add/Drop Multiplexers (ADMs) when they are connected logically in a mesh topology. A self-healing algorithm is also proposed for network restoration. It offers good performance in terms of protection line-capacity, restoration delay, and survivability against multiple failures.

The goal of this research, as an integral component of virtual space teleconferencing systems, is to generate three-dimensional facial models from facial images and a to synthesize images of the models virtually viewed from different angles. Since there is a great gap between the images and 3 D model, we argue that it is necessary to have a base face model to provide a framework. The base model is built by carefully selecting and measuring a set of points on the face whose corresponding points can be readily identified in the input images, and another set of points that can be determined from the first point set. The input images are a front view and a side view of the face. First the extremal boundaries are extracted or interpolated, and the face features such as eyes, nose and mouth are extracted. The extracted features are then matched between the two images, and their 3 D positions calculated. Using these 3 D data, the prepared base face model is modified to approximate the face. Finally, images of the modified 3 D model are synthesized by assuming new virtual viewing angles. The originality and significance of this work lies in that the face model can be automatically generated.

Using the chirped grating with temperature control, we demonstrated the adaptive dispersion compensation at 40 Gbit/s RZ transmission. The simple monitoring of the 40 GHz frequency component enables us to automatic control of the adaptive dispersion compensator.

Using the chirped grating with temperature control, we demonstrated the adaptive dispersion compensation at 40 Gbit/s RZ transmission. The simple monitoring of the 40 GHz frequency component enables us to automatic control of the adaptive dispersion compensator.

This paper describes a new multiple DmB1C (Differential m Binary 1 Complement insertion) /DmB1M (Differential m Binary with 1 Mark insertion) coding scheme for high-speed optical multiplex transmission. The coding scheme has the characteristics of small consecutive identical digits and a good balance between marks and spaces. Furthermore, it has also good synchronization characteristics and higher flexibility for extension to high capacity transmission than the conventional mB1C or DmB1M coding schemes. We describe a design methodology for a multiplex transmission system using the proposed coding scheme, and verify the characteristics of the proposed coding scheme using an experimental setup of a 2.8 Gbit/s serial optical interconnection circuit, which has 16 parallel 156 Mbit/s inputs. The coding scheme realizes transmission systems with simple analog circuit configuration, and small digital circuit complexity with wide dynamic range and good mark ratio tolerance.

This paper proposed a fault localization and supervisory (SV) channel implementation for linear-repeaters (L-Reps) employing optical line amplifiers. In order to successfully introduce L-Reps into a Synchronous Digital Hierarchy (SDH)/Synchronous Optical Network (SONET)-based networks in a smooth, orderly fashion, layering of repeater section and supervisory system design must be taken into consideration. There supervisory techniques, such as linking analog-based and digital-based information, a precedence of digital-based information and an upstream precedence, for locating faulty L-Rep sections are proposed taking into consideration the difference in monitoring capabilities between L-Reps and regenerating-type repeaters (R-Reps). Furthermore, a linear repeater supervisory (LSV) channel configuration for L-Reps is also proposed. Finally, an SV system established in a prototype SDH-based 10-Gbit/s optical transmission system is briefly described.

Methodologies for more efficient Raman amplification and a more suitable modulation format for 40 Gbit/s WDM unrepeatered transmission are investigated. Management of the fiber effective area is proposed to realize low noise distributed Raman amplification. An Aeff management technique in which low-Aeff fiber is located in a median section instead of the last section, was confirmed numerically and experimentally to improve the OSNR and Q-factor. Carrier-suppressed-return-to-zero (CS-RZ) modulation has the advantage of reducing fiber-nonlinearity effects and permitting denser multiplexing of the wavelengths. 40 Gbit/s 32-channel unrepeatered WDM transmission over 202 km was demonstrated employing the proposed methodologies.

This paper presents a design for a 1.55 µm, 450 Mbit/s high-sensitivity receiver, employing an InGaAs/InGaAsP/InP-APD and a high-impedance preamplifier with a GaAs MESFET front-end circuit. Studying Ge-APDs and InGaAs/InGaAsP/InP-APDs, it is confirmed that InGaAs/InGaAsP/InP-APDs are suitable for the wavelength region around 1.55 µm and transmission bit rates near 450 Mbit/s. Further studies on InGaAs/InGaAsP/InP-APDs confirm that they should be used in the lower multiplication reqion: e.g. less than 15. Using a InGaAs/InGaAsP/InP-APD and a high-impedance preamplifier, a receiver sensitivity of -42.9 dBm at a bit error rate of 10-11 is realized. Applying this receiver with a high power optical source, a stable longitudinal spectrum distributed feedback laser diode (DFB-LD), a 450 Mbit/s transmission experiment over 210 km distance is successfully carried out.

A framework for the visual representation of three-dimensional free-form curved surfaces based on a special class of surface curves, herein called the surface structure curves, is in progress. By analyzing their properties, we attempt to construct a basis for describing the topographical structures of curved surfaces which give a global description of the surface geometry. Surface structure curves are a set of surface curves defined by using viewpoint-invariant features-surface curvatures (and their gradients and asymptotes) from differential geometry. From these surface structure curves, surface sketches by means of the topographical structure of ridge lines, valley lines and the enclosing boundaries of bumps and dents can be inferred. This paper proposes a view-point invariant representation scheme which provides a smooth surface sketch",--a natural parameterization of free-form curved surfaces. We define three types of surface structure points and five types of surface structure curves in terms of zero-crossings, asymptotes and gradients of the Gaussian and mean curvatures. We discuss their properties and usefulness in edge based segmentation and description of free-form curved surfaces. Some examples of surface sketches using the surface structure curves are shown.